Wouldn't it be if the camera's x, y, or z rotation is greater than PI?
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ShmiddtyNov 19 '12 at 18:21

Alternatively, you could just rotate the mesh in the opposite direction of the camera whenever the camera rotates so that it always front-facing.
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ShmiddtyNov 19 '12 at 18:22

It's a little more complicated than that. The label's parent Object3d rotates freely, and the camera orbits a separate point (completely independent of the parent object).
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Aaron LamprosNov 19 '12 at 20:04